A technique for imaging a driver's face for the purpose of detecting a driver's look direction and/or blinks based on an analysis of a face image is disclosed, for example, in Japanese patent document JP-A-H11-331653. Further, a face camera for imaging the driver's face in a normal position for reading driving support information (e.g., a speed of the vehicle, a warning or the like) is disposed on a back of an instrument panel that displays the driving support information in a manner disclosed in, for example, Japanese patent document JP-A-2000-168502.
When the face camera in a meter device is recognizable by the driver of the vehicle, the notion of being watched by the camera possibly affects the driver of the vehicle negatively in a psychological sense. That is, the face camera is preferably disposed to be invisible from the driver of the vehicle. The camera in the second disclosure described above makes it difficult to recognize the camera from outside of the meter device with a half mirror interposingly disposed on a light axis of the camera.
However, the half mirror structure describe above allows about 50% of light to be passed to the camera portion due to the optical characteristics of the half mirror, thereby making it impossible to prevent the existence of the camera from being recognized from the driver of the vehicle. Further, the half mirror only allows about 50% of light to reach the camera portion disposed in an inside of the meter device, thereby making it difficult to analyze the image captured by the camera in subsequent processes.